In wireless communication, equalization is performed on the receiver side to remove intersymbol interference due to multipath propagation. As concrete techniques of the equalization, there are time domain equalization and frequency domain equalization. It is known that the frequency domain equalization is superior to the time domain equalization.
To perform the frequency domain equalization, it is required to provide FFT for performing frequency conversion on the channel impulse response of an estimated propagation channel and FFT for converting time domain data into frequency domain data, to perform equalization based on the output signal of each FFT.
Accordingly, the receiver requires computing circuits for two types of FFT, which leads to a problem of increase in circuit scale.
If one FFT is used to perform frequency conversion both on channel impulse response and data, which are different in the number of input bits to FFT, accuracy of frequency conversion performed by FFT may be deteriorated. For example, when the input bit width for FFT is optimized for data frequency conversion, the input bit width for FFT may possibly become insufficient depending on the effective length of channel impulse response, which leads to a problem that calculation accuracy of frequency response of channel impulse response is deteriorated.